Mild One-Step Synthesis of Dibromo Compounds from Cyclic Ethers.

A novel one-step method for mildly converting cyclic ethers into dibromo compounds is reported. Alcohols, oximes, aldehydes, and ketones are known to react under Appel or Corey–Fuchs reaction conditions, but apparently these have never been applied to oxetanes or larger cyclic ethers. Treatment of 3,3-dimethyloxetane (1) with tetrabromomethane and triphenylphosphine gave the corresponding dibromo compound 1,3-dibromo-2,2-dimethylpropane (2). The less-strained homologue oxolane (6) was also reacted giving 1,4-dibromobutane (7) in a 93% yield. Mechanistic interpretations are offered to explain the observed reaction rates of the conversions described.